21 day rolling Average - DAX Measure

[Invesco]

Hi Experts

I cannot see my error when trying to work out the 21 day moving average based on the date as show below...

Here is my measure 

3 Week Rolling Trend =

VAR NumDays = 21

VAR Rolling =

CALCULATE(

[Weekly Rates],

DATESINPERIOD('act_rates_activity_volume_and_cf_days'[Date],LASTDATE('act_rates_activity_volume_and_cf_days'[Date]),-NumDays,DAY)

)

Return

Divide(Rolling,NumDays)

[lbendlin · Accepted solution]

You're supposed to use your Dates table for this.

DATESINPERIOD function (DAX) - DAX | Microsoft Docs